This article explores the utility of respondent self-evaluation of ideological position on a liberal-conservative scale as a predictor of vote relative to two other types of predictors: party identification and issue positions. The general conclusion is that ideological self-evaluation identifies an effect that is independent of the other two predictors in the electorate as a whole but that the extent of this effect can vary substantially, depending on the context of the campaign and the social grouping being considered. As expected, its effect was more pronounced in 1972 than 1968, or 1964.